I went to the Dr yesterday and he told me to ween my 13 mo old. he said he didn't think it was a good idea to nurse and grow a baby at the same time. I know other people have done it. Give me some feedback mamas!

Your body will take what it needs to nourish the fetus first. The other reason they give, is that it will cause contractions but they are so small that it will not harm the baby. I believe orgasms cause even bigger contractions and they do not advise against sex, unless you are high risk.

Just make sure that you eat right and get plenty of fluids and rest. Be prepared to have sore nipples and possibly a drop in your supply.

I nursed for 5 months into my pregancy. My MW fully supported me in that!! Sooooo many people nurse while pregnant, unless their is a medically reason why you should not, I would continue. If you are feeling extra tired etc. You can double up on your prenatal! (My MW told me that)

it is perfectly fine unless you are have had problems with multiple miscarriages or have had problems with preterm labor. Most docs are either have little knowledge on the subject and/or are erring on the side of caution to cover themselves.
If you were to have any complications of any kind even if they weren't related to breastfeeding it could come back to bite him if he told you that there would be no problems...

So as long as you are healthy and have no bad pregnancy history then all is well. I have nursed during 2 pregnancies with no problem at all! It is a wonderful experience.
There is lots of info on kellymom.com about it.

I got pg with dd1 when ds was only 9 months, and he was still nursing strong. My ob told me as I could nurse him as long as I wanted, just to drink a lot of water and eat a little bit more. (She nursed until she was 8 months pg with her 2nd.) I was high risk (not for preterm labor), and it still wasn't a problem. I ended up weaning him when I was 4 months along.

Now, while you're pregnant. Your current milk will probably go away so that the colostrum can be made. You could be completely milkless for as little as a week or as long as months. And when the colostrum comes in, it will have a laxative effect on your current LO. I've never nursed while pregnant, just taking this information from what people who have done so have told me.